Chesapeake Energy Corp. lost more than $14 billion in 2015, as it wrote down the value of its oil and gas fields amid a protracted downturn in energy prices that has ravaged the company’s stock. Shares of Chesapeake—which have fallen 60% over the past three months amid balance sheet concerns—rose more than 15% to $2.56 in morning trading as the company’s 53% drop in revenue was slightly better than expected. The company also said it…